History’s 10 Most Legendary Uncracked Codes

From five lines of letters scrawled on the back of a dead man’s book to the taunting codes sent to police by the Zodiac Killer, some of history’s most legendary uncracked codes and ciphers represent a fascinating and frustrating challenge even for the world’s brightest cryptographers.

Could the Beale Papers lead to buried treasure? How does the Chaocipher work? Perhaps we’ll never know.